Huffman, who starred in Mamet's play "Speed-the-Plow" in the late 1980s, was among 50 people charged in the largest-ever college admissions conspiracy prosecuted by the DOJ. The agency has accused her of paying $15,000 to a made-up charitable organization in exchange for helping her elder daughter to cheat on her college admissions exam, partly based on phone recordings of her conversations with a cooperating witness.

While Macy was not charged, an affidavit says Huffman's "spouse" participated in conversations at their Los Angeles home with a confidential witness about the scheme.

Mamet came to Huffman's defense in an open letter, attributing her actions to "a parent’s zeal for her children’s future," calling the college admissions process "an unfortunate and corrupt joke."

He continued, "Unqualified (students) may be accepted for many reasons, among them, as Legacies, and on account of large donations made by their parents. I do not see the difference between getting a kid into school by bribing the Building Committee, and by bribing someone else. But, apparently, the second is against the Law. So be it."

He wrote that he was "crazy" about both Huffman and Macy, both of whom he's known for over three decades.

"If ever there were a use for the Texas Verdict, this is it," he added. "For the uninitiated, the Texas Verdict is: 'Not Guilty, but Don’t do it Again.'"